thoracopagus

noun
tho·​ra·​cop·​a·​gus | \ ˌthōr-ə-ˈkäp-ə-gəs, ˌthȯr- How to pronounce thoracopagus (audio) \
plural thoracopagi\ -​ˌjī \

Medical Definition of thoracopagus

: conjoined twins that are united at the thorax